<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>结构伪类选择器-公式用法</title>
    <style>
        /* 偶数 */
         /* li:nth-child(2n){
            background-color: green;
         } */
          /* 奇数标签 */
          /* li:nth-child(2n-1){
            background-color: green;
          } */
           /* 5的倍数 */
          /* li:nth-child(5n){
            background-color: green;
          } */
           /* 找5之后的标签 */
          /* li:nth-child(n+5){
            background-color: green;
          } */
           /* 找5以前的标签 */
          li:nth-child(-n+5){
            background-color: green;
          }
    </style>
</head>
<body>
    <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>6</li>
        <li>7</li>
        <li>8</li>
        <li>9</li>
        <li>10</li>
    </ul>
</body>
</html>